The original function of a sock (or a pair of socks) is to prevent abrasion damage that is caused due to direct contact between the inside face of the shoe and the foot when the shoe is worn.
Therefore, in order to prevent abrasion of the foot with a strong force that occurs when relative movement occurs between the sock and the foot, the sock was formed conventionally of a soft fabric. And, as a typical fabric for such use, knitted fabric is commonly employed.
On the other hand, if there occurs e.g. excess of the fabric due to mismatch between the sock and the foot, when the shoe is worn, the excess fabric will exert pressure to the foot locally, thus giving unnatural feel.
Therefore, in order to obtain a shape that maximally matches the foot shape, there has long been employed a construction wherein a bag-like toe section or heel portion is joined to a tubular foot section.
Meanwhile, in the relationship between a shoe and a foot, not only agreement of length, but also agreement of lateral width is important. Regarding the issue of agreement or non-agreement of lateral width, it is said that a lateral width is suitable if it provides contact between the lateral face of the big toe and the inner face of the shoe, but which causes no compression therebetween.
That is, the base of the big toe and the lateral face adjacent thereto are portions which are to be constantly placed in contact with the shoe via the sock. In the case of the conventional socks disclosed in Patent Documents 1 and 2, at this portion, there exist at least a portion of circumferential edge of the knitted fabric and a join line to which this circumferential edge portion is joined.
Such join line lacks the elasticity inherent in the knitted fabric. Hence, in spite of use of knitted fabric having flexibility, there was possibility of giving the big toe base portion a damage such as an abrasion damage. Especially, when a violent movement such as a sporting activity is effected, such damage would appear more conspicuously.